1. Field of the Invention
The present invention relates to a thin-film magnetic head which performs a magnetic recording action by a perpendicular recording scheme, a method of manufacturing the same, a head gimbal assembly, and a hard disk drive.
2. Related Background Art
In recent years, hard disk drives have remarkably been improving their areal recording density. The areal recording density of hard disks has recently reached and is about to exceed 160 to 200 GB/platter in particular. In keeping with this trend, thin-film magnetic heads have been required to improve their performances.
The thin-film magnetic heads can roughly be classified according to their recording schemes into those of longitudinal magnetic recording type and those of perpendicular magnetic recording type. The longitudinal magnetic recording scheme records data in a (longitudinal) direction within a recording surface of a hard disk (recording medium), while the perpendicular magnetic recording scheme records data such that the direction of recording magnetization formed in the hard disk is made perpendicular to the recording surface. The thin-film magnetic heads of perpendicular magnetic recording type have been considered more promising than those of longitudinal magnetic recording type, since they can realize a much higher recording density than that in the longitudinal magnetic recording scheme, while their recorded hard disks are less susceptible to heat fluctuation.
Conventional thin-film magnetic heads of perpendicular magnetic recording type are disclosed in U.S. Pat. Nos. 6,504,675, 4,656,546, and 4,672,493 and Japanese Patent Application Laid-Open No. 2004-94997, for example.
Meanwhile, a conventional magnetic head of perpendicular magnetic recording type (perpendicular magnetic recording head which will also be referred to as “PMR” in the following) has a magnetic pole layer and a thin-film coil. The magnetic pole layer generates a recording magnetic field for recording data onto a recording medium by the perpendicular magnetic recording scheme. The thin-film coil generates a magnetic field corresponding to the data to be recorded on the recording medium.
As such a PMR, one equipped with a write shield layer has conventionally been known as described in U.S. Pat. No. 4,656,546. The PMR equipped with the write shield layer has a structure shown in FIG. 39, for example. FIG. 39 is a sectional view showing the structure of a conventional PMR 500.
This PMR 500 has an insulating layer 501, a main magnetic pole layer 502, a medium-opposing surface (air bearing surface, which will also be referred to as “ABS”) 503, and a gap layer 504. The PMR 500 also has a write shield layer 505, a thin-film coil 506, a photoresist 507, and a connecting part 508 connecting the main magnetic pole layer 502 and write shield layer 505 to each other.
The main magnetic pole layer 502 is formed on the insulating layer 501 and has a magnetic pole end part arranged on the ABS 503 side. The write shield layer 505 is magnetically connected to the main magnetic pole layer 502 at a position remote from the ABS 503, and opposes the main magnetic pole layer 502 while interposing the gap layer 504 therebetween on the ABS 503 side. The thin-film coil 506 is wound like a flat spiral about the connecting part 508, while their turns are insulated from each other by the photoresist 507.
The main magnetic pole layer 502 and write shield layer 505 are formed from a magnetic material, while the gap layer 504 is made of an insulating material such as alumina (Al2O3). The thin-film coil 506 is formed from a conductive material such as copper.